Panuska J R, Parker C W
Anal Biochem. 1987 Jan;160(1):192-201. doi: 10.1016/0003-2697(87)90630-0.
The use of the aliphatic aldehyde, para-hydroxyphenylacetaldehyde as the reactive moiety in the radioiodination of proteins by reductive alkylation is described. The para-hydroxyphenyl group is radiolabeled with 125I, reacted through its aliphatic aldehyde group with primary amino groups on proteins to form a reversible Schiff base linkage which can then be stabilized with the mild reducing agent NaCNBH3. The introduction of the methylene group between the benzene ring and the aldehyde group increases its reactivity with protein amino groups permitting efficient labeling at low aldehyde concentrations. Using this method, radioiodinated proteins with high specific activity can be produced. The reductive alkylation procedure is advantageous in that the labeling conditions are mild, the reaction is specific for lysyl residues, and the modification of the epsilon-ammonium group of lysine results in ionizable secondary amino groups avoiding major changes in protein charge.
描述了使用脂肪族醛对羟基苯乙醛作为反应基团，通过还原烷基化对蛋白质进行放射性碘化的方法。对羟基苯基用¹²⁵I进行放射性标记，其脂肪族醛基与蛋白质上的伯氨基反应形成可逆的席夫碱键，然后用温和的还原剂氰基硼氢化钠使其稳定。苯环和醛基之间引入亚甲基增加了其与蛋白质氨基的反应性，允许在低醛浓度下进行有效标记。使用这种方法，可以产生具有高比活性的放射性碘化蛋白质。还原烷基化方法的优点在于标记条件温和，反应对赖氨酰残基具有特异性，赖氨酸ε-铵基团的修饰产生可电离的仲氨基，避免了蛋白质电荷的重大变化。
